The invention relates generally to suspension systems for vehicles and more particularly to a novel control valve mechanism for regulating the air pressure within a vehicle air spring thereby functioning to increase the spring rate when the air spring is being compressed on curves and bumpy road surfaces.
The use of air springs to replace conventional steel springs between the sprung mass and the unsprung mass of a vehicle to support the chassis and body of the vehicle upon a running gear is now well known in the art. These air springs consist of an expansable chamber that receives air under pressure of a value suitable to support the chassis or a vehicle upon the running gear, utilizing the air of the air spring as the resilient means for supporting the body upon the running gear of the vehicle. To establish a predetermined clearance height between the sprung mass, that is, the body of the vehicle, and the unsprung mass, that is, the running gear of the vehicle, the air springs receive air under pressure from a suitable source of pressure supply on the vehicle sufficient to support the load of the body upon the running gear at a predetermined clearance height relative to the running gear.
In the past various types of control valve mechanisms have been developed for regulating the air pressure within a vehicle air spring. Some of these are illustrated in U.S. Pat. Nos. 2,910,305, 2,970,614, and 3,145,032. The control valve mechanisms in these structures are directed toward load-leveling systems that incorporate structure to provide a time delay for the responsiveness of the system or structure for selectively deactivating the control valve mechanism. Another variation is illustrated in U.S. Pat. No. 2,965,391 wherein the control valve is constructed and arranged to provide for establishing and maintaining more than one clearance type value between the sprung mass and the unsprung mass of the vehicle so as to increase the road clearance of the vehicle when desired.
It is an object of the invention to provide a novel control valve mechanism for a vehicle air suspension system that will function to increase the spring rate of the air spring when it is being compressed on curves and bumpy road surfaces.
It is also an object of the invention to provide a novel control valve mechanism for a vehicle air suspension system in which the valve will be fully closed at a point prior to full axle travel to provide the maximum spring rate at that time.
It is another object of the invention to provide a novel control valve mechanism for a vehicle air suspension system which will reduce the load on the cushioning stop member within the air spring thus allowing a softer stop member to be used which will reduce the shock when the spring bottoms.
It is another object of the invention to provide a novel control valve mechanism for a vehicle air suspension system that would allow a large air reservoir to be used to give a soft spring rate near the center of the axle motion, but increasingly firmer spring rates at the extreme positions of axle travel.
It is a further object of the invention to provide a novel control valve mechanism for a vehicle air suspension system that would have a minimum number of components which can be easily and economically manufactured and assembled.